1. Field of the Invention
This invention relates to a method for quantifying porosity of parts, particularly parts of simple and complex geometries.
2. The Prior Art
In the fabrication of parts, e.g., metal or composite parts, it is often important to know the porosity thereof as the more porous parts are lighter and structurally weaker, while the less porous parts are heavier, stronger, and more thermally conductive. While more porous parts have their uses e.g., in lightweight or insulative structures, excess porosity is a detriment in aircraft engines, including gas turbine engines. Accordingly, it is important to have a reliable method for quantifying the porosity of parts in various structures, e.g. in gas turbine engines.
Prior art inspection methods can quantify porosity in parts of relatively simple geometry. Thus, ultrasonic methods which employ a part-contacting probe or a microfocus x-ray method can quantify porosity on flat walled parts and e.g. cylinder walls but cannot accurately guage complicated geometries. These complicated geometries include parts of small, tight, or decreasing radii such as the curved flange at the end of a gas turbine engine housing. An example of such housing is shown as housing 10 in FIG. 2 with its cylindrical walls 12 and end flange 14 of small and changing radii of curvature. Accordingly it is important to quantify the porosity both at engine housing wall 12 and curved flange 14 for accurate inspection thereof.
In other prior art, Japanese patent 63-58242 (1988) directs a focused laser beam at a sample to measure the thermal-diffusivity thereof using a quadratic equation. There is also Soviet patent 873087 (1981) which applies heat to a sample and compares the temperature change on both sides of such sample to obtain the coefficient of heat conductivity thereof. Then there is Soviet patent 1318886 (1987) which discloses applying a pulse heating source to a sample and records the temperature increase to the reverse side thereof for monitoring of thermal conductivity.
None of the above references suggests measuring or quantifying the porosity of a sample whether of simple or complex geometry.
However, as noted above, there is a need and market for accurately measuring or quantifying the porosity of non metallic parts including composite parts of complex geometry, which method substantially overcomes the above prior art shortcomings.
There has now been discovered a method which quantifies the porosity of a non metallic part including a composite part of simple or complex geometry, without damaging or contacting such part, to the end that such part can be accurately inspected for use or non-use.